Transportation box

The space Inside the box starts at 10*10*10 and grows 2 feet with every 3 levels 

It has no air and all oxygen is sucked out once closed and if something living that needs air goes in it starts to take 3d4 damage if no oxygen is provided 

if you have this spell there are two ways of accessing someone else’s box the fist is that link there box with yours and than you can put things in theirs but can’t take things out. The other is if you are level 15 you have to use a platinum coin and wait a long rest to force your way into the space it can de countered with a wisdom or intelligence saving roll against the caster